"qpos” observation info consult

[FanZhang91]

  I'm confused by qpos info. I hope you can help me.
  From the paper，i known that  "qpos" means current observation produced by leader arms(corresponds to the “joints” variable in the network architecture diagram) and current action info is produced by follower arms(actual gripper arms).

In my understanding, leader arms should not exist in inference stage. Why is qpos(leader arms observation info) rather than current followers obervation info(actual gripper arms observation info) is send to the transformer network?